osqp-eigen: Devel breaks idyntree::optimal_control

The first error is the following

t searching for unused variables given on the command line.
loading initial cache file /home/sdafarra/Software/robotology-superbuild/build/robotology/iDynTree/CMakeFiles/YCMTmp/iDynTree-cache-Release.cmake
-- Found Eigen3: /usr/include/eigen3 (Required is at least version "3.2.92") 
-- Found YARP: /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/YARP (found version "3.3.2+43-20200411.3+gita33cf54b1")
-- Found YARP: /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/YARP (found version "3.3.2+43-20200411.3+gita33cf54b1")
-- Using iCub from install
-- Found YARP: /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/YARP (found version "3.3.2+43-20200411.3+gita33cf54b1")
CMake Error at /usr/share/cmake-3.16/Modules/CMakeFindDependencyMacro.cmake:47 (find_package):
  By not providing "FindEigen.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Eigen", but
  CMake did not find one.

  Could not find a package configuration file provided by "Eigen" with any of
  the following names:

    EigenConfig.cmake
    eigen-config.cmake

  Add the installation prefix of "Eigen" to CMAKE_PREFIX_PATH or set
  "Eigen_DIR" to a directory containing one of the above files.  If "Eigen"
  provides a separate development package or SDK, be sure it has been
  installed.
Call Stack (most recent call first):
  /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/OsqpEigen/OsqpEigenConfig.cmake:23 (find_dependency)
  cmake/iDynTreeDependencies.cmake:51 (find_package)
  cmake/iDynTreeDependencies.cmake:91 (idyntree_handle_dependency)
  CMakeLists.txt:43 (include)


-- Configuring incomplete, errors occurred!
See also "/home/sdafarra/Software/robotology-superbuild/build/robotology/iDynTree/CMakeFiles/CMakeOutput.log".
make[2]: *** [CMakeFiles/iDynTree.dir/build.make:104: robotology/iDynTree/CMakeFiles/YCMStamp/iDynTree-configure] Error 1
make[1]: *** [CMakeFiles/Makefile2:1108: CMakeFiles/iDynTree.dir/all] Error 2
make: *** [Makefile:95: all] Error 2

which can be easily solved by changing https://github.com/robotology/osqp-eigen/blob/devel/CMakeLists.txt#L110 to

list(APPEND OSQP_EIGEN_EXPORTED_DEPENDENCIES osqp Eigen3)

but if I try to compile again I get the following error

[ 25%] Performing configure step for 'iDynTree'
Not searching for unused variables given on the command line.
loading initial cache file /home/sdafarra/Software/robotology-superbuild/build/robotology/iDynTree/CMakeFiles/YCMTmp/iDynTree-cache-Release.cmake
-- Found YARP: /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/YARP (found version "3.3.2+43-20200411.3+gita33cf54b1")
-- Found YARP: /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/YARP (found version "3.3.2+43-20200411.3+gita33cf54b1")
-- Using iCub from install
-- Found YARP: /home/sdafarra/Software/robotology-superbuild/build/install/lib/cmake/YARP (found version "3.3.2+43-20200411.3+gita33cf54b1")
-- Found Eigen3: /usr/include/eigen3 (Required is at least version "2.91.0") 
CMake Warning (dev) at /usr/share/cmake-3.16/Modules/FindOpenGL.cmake:275 (message):
  Policy CMP0072 is not set: FindOpenGL prefers GLVND by default when
  available.  Run "cmake --help-policy CMP0072" for policy details.  Use the
  cmake_policy command to set the policy and suppress this warning.

  FindOpenGL found both a legacy GL library:

    OPENGL_gl_LIBRARY: /usr/lib/x86_64-linux-gnu/libGL.so

  and GLVND libraries for OpenGL and GLX:

    OPENGL_opengl_LIBRARY: /usr/lib/x86_64-linux-gnu/libOpenGL.so
    OPENGL_glx_LIBRARY: /usr/lib/x86_64-linux-gnu/libGLX.so

  OpenGL_GL_PREFERENCE has not been set to "GLVND" or "LEGACY", so for
  compatibility with CMake 3.10 and below the legacy GL library will be used.
Call Stack (most recent call first):
  src/visualization/CMakeLists.txt:63 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Could NOT find Doxygen (missing: DOXYGEN_EXECUTABLE) 
-- Configuring done
CMake Error at src/optimalcontrol/CMakeLists.txt:107 (add_library):
  Target "idyntree-optimalcontrol" links to target "Eigen3::Eigen" but the
  target was not found.  Perhaps a find_package() call is missing for an
  IMPORTED target, or an ALIAS target is missing?


CMake Error at src/optimalcontrol/CMakeLists.txt:107 (add_library):
  Target "idyntree-optimalcontrol" links to target "Eigen3::Eigen" but the
  target was not found.  Perhaps a find_package() call is missing for an
  IMPORTED target, or an ALIAS target is missing?


-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.
make[2]: *** [CMakeFiles/iDynTree.dir/build.make:104: robotology/iDynTree/CMakeFiles/YCMStamp/iDynTree-configure] Error 1
make[1]: *** [CMakeFiles/Makefile2:1108: CMakeFiles/iDynTree.dir/all] Error 2
make: *** [Makefile:95: all] Error 2

It seems weird since Eigen3::Eigen should be added when finding Eigen3.

@GiulioRomualdi @traversaro